Injection Pump Return

[White Knight]

I’m trying to decide how to route the return flow from the injection pump for my FASS system. None of the directions for the p-pump trucks say much about the return system. It would seem that the return would want to be addressed so that you get the FASS return to open and allow it to perform as designed. I’ve got a 150/200? And want to run it at 45psi max which is more than the stock return will take. I’ve got a few ideas on how to route the system, I just can’t decide which one to choose :bang

Option A: Route the IP supply according to FASS directions, and run the return from the other side of the pump through a regulator set at 30psi w/ a 1:1 boost reference. This would allow the system to be under more mild pressures during low power situations, and would circulate any air introduced into the system during installation or filter changes to be returned to the tank. And when 15psi of boost is reached the FASS regulator will take over and let the FASS do its thing. There seems to be a few members on this site that do it this way.

Option B: Run the supply fuel to the pump and return through a valve. If I left the valve just cracked open to flow a minimal amount it would circulate fuel while letting the FASS do its thing. But the FASS would be at full pressure constantly.

Option C: Run the supply fuel to the IP and dual feed it through the stock inlet and return port. This would run at full pressure the entire time and any air would have to be run through the IP and injectors.


Any advise or better options? Thank you and sorry about the long post :thankyou2:

Thanks,
Derek

 

[zstroken]

Option A. Issue with C is that you will have very little flow through the injection pump at idle.

 

[White Knight]

Thanks, that's the one I'm leaning towards

You run a setup similar to A don't you?

 

[zstroken]

Yes.

 

[Diesel-Dan]

I’m trying to decide how to route the return flow from the injection pump for my FASS system. None of the directions for the p-pump trucks say much about the return system. It would seem that the return would want to be addressed so that you get the FASS return to open and allow it to perform as designed. I’ve got a 150/200? And want to run it at 45psi max which is more than the stock return will take. I’ve got a few ideas on how to route the system, I just can’t decide which one to choose :bang

Option A: Route the IP supply according to FASS directions, and run the return from the other side of the pump through a regulator set at 30psi w/ a 1:1 boost reference. This would allow the system to be under more mild pressures during low power situations, and would circulate any air introduced into the system during installation or filter changes to be returned to the tank. And when 15psi of boost is reached the FASS regulator will take over and let the FASS do its thing. There seems to be a few members on this site that do it this way.

Option B: Run the supply fuel to the pump and return through a valve. If I left the valve just cracked open to flow a minimal amount it would circulate fuel while letting the FASS do its thing. But the FASS would be at full pressure constantly.

Option C: Run the supply fuel to the IP and dual feed it through the stock inlet and return port. This would run at full pressure the entire time and any air would have to be run through the IP and injectors.


Any advise or better options? Thank you and sorry about the long post :thankyou2:

Thanks,
Derek

OR Option D:

Get a one way flow control valve (This one you would need to run a check valve with) and put on the P-7100 Return line.

THEN get a 20 PSI Spring for the FASS. Plumb your external regulator on the FASS return line going back to the tank and hook up boost reference. That way the FASS is the one controlling pressure and you are not cutting off FASS return (Which is VERY important for our pump operation) at any time.

That would be the way i would do it if i was going the direction you are.

Not unlike they way i would do a PSD if i had one.....

I have a few D-max guy running it this way....and they LOVE it....

 

[GOT-Torque]

Diesel Dan,

Would there be any problems with option A? It wouldn't be "cutting off the FASS return" as you stated. If would actually allow full flow (maximum cooling of the injection pump) until boost would rise in which the FASS pump would be allowed to reach 45 psi...

maybe I'm missing something...

 

[Diesel-Dan]

Diesel Dan,

Would there be any problems with option A? It wouldn't be "cutting off the FASS return" as you stated. If would actually allow full flow (maximum cooling of the injection pump) until boost would rise in which the FASS pump would be allowed to reach 45 psi...

maybe I'm missing something...

Well your pressure is only going to be as high as your lowest regulator setting. For example....in the 200 GPH FASS. We have 2 regulators: The High pressure relief in the T-block set at 80 PSI and the lower regulator that controls pressure...lets say 45 PSI. You will only see 45 PSI in this pump because its bleeding fuel back to the tank once 45 PSI of resistance is met. The only time the high pressure relief would kick in is if you dead headed the return line going back to the tank from the FASS.

SO if you put a regulator at the P-Pump return set at 20 PSI, it would take over pressure control and the FASS return would stop returning fuel back to the tank as the regulator at the head would be flowing excess pump volume back through the stock engine return line...which i doubt you would get that low due to line restriction....or might.....

SO for the FASS to return fuel, you need a regulator set at or above the FASS regulator pressure.

OR set your return flow via the valve and put your variable restricion on the FASS return line. I feel this would work best...

 

[GOT-Torque]

The setup I'm putting together is just like zstroken's (Option A) above. I think he said the lowest psi he can see is around 30 psi. In this scenario, with the FASS not sending any fuel thru it's own return to the tank, does it hurt anything?

I'm not argueing that this is a better way than your option D, just wanting to know if it will damage anything. I've already plumbed everything and wasn't hoping to change it...

 

[White Knight]

OR Option D:

Get a one way flow control valve (This one you would need to run a check valve with) and put on the P-7100 Return line.

THEN get a 20 PSI Spring for the FASS. Plumb your external regulator on the FASS return line going back to the tank and hook up boost reference. That way the FASS is the one controlling pressure and you are not cutting off FASS return (Which is VERY important for our pump operation) at any time.

That would be the way i would do it if i was going the direction you are.

Not unlike they way i would do a PSD if i had one.....

I have a few D-max guy running it this way....and they LOVE it....

You mean put the regulator here?

I'm doing a 3/8" return line and removing all factory components, if it matters.

The only question I have about your option is how to limit top end pressure. The max pressure I want to see is 50psi, and I don't know of a diesel rated regulator that has a reference option and 5psi-50psi range

This was similar to my second way of doing option B, but again, I'm not sure how to successfully run the referenced regulator second in series with the FASS spring. With two external regulators in parallel it would be easy, but $$$

 

[zstroken]

With the one way valve what are you doing with it? Just restricting the p7100 slightly? If so you could just use an orifice also.

 

[Diesel-Dan]

The setup I'm putting together is just like zstroken's (Option A) above. I think he said the lowest psi he can see is around 30 psi. In this scenario, with the FASS not sending any fuel thru it's own return to the tank, does it hurt anything?

I'm not argueing that this is a better way than your option D, just wanting to know if it will damage anything. I've already plumbed everything and wasn't hoping to change it...

As far as pump damage.....no.....BUT as far as a big waste of money...yes. You paid for the function of the FASS. Air removal and superior fuel filtering. When you cut off the return flow back to the tank...you loose all of that and you have an $800.00 HPFP at that point. The % of WOT to not is VERY lop sided...you prob spend about 2% if that on full throttle.....so 98% of the time the FASS would not be doing its thing that you paid for....

You mean put the regulator here?

I'm doing a 3/8" return line and removing all factory components, if it matters.

The only question I have about your option is how to limit top end pressure. The max pressure I want to see is 50psi, and I don't know of a diesel rated regulator that has a reference option and 5psi-50psi range

This was similar to my second way of doing option B, but again, I'm not sure how to successfully run the referenced regulator second in series with the FASS spring. With two external regulators in parallel it would be easy, but $$$

Exactly....you would use the FASS regulator to set your low pressure and then open up the external regulator to just start restricting the flow.

As for the Boost reference...this might need to be played with some. The way you could tune this is with an air regulator set to the PSI that would stick you at 50 PSI of fuel pressure under full boost. This could be very easily set with an air hose off a compressor with our pump running. You could mount this under the hood. I know if some regulators that give you, for example 1:1, 1:2, 1:5, 1:10 boost ratios. I think they tune with orifices...but don’t quote me on that.

With the one way valve what are you doing with it? Just restricting the p7100 slightly? If so you could just use an orifice also.

Well the one way valve keeps a check on the system...it will not let it bleed back and loose prime. The return circuit is usually on the high side of the pump, so prime should no be lost. AND yes, you could use an orifice.....that is basically what a flow control valve is more or less. A tunable orifice. (I can hear the :shake: jokes now….LOL) BUT you will still need to check the return flow.

 

[GOT-Torque]

As far as pump damage.....no.....BUT as far as a big waste of money...yes. You paid for the function of the FASS. Air removal and superior fuel filtering. When you cut off the return flow back to the tank...you loose all of that and you have an $800.00 HPFP at that point. The % of WOT to not is VERY lop sided...you prob spend about 2% if that on full throttle.....so 98% of the time the FASS would not be doing its thing that you paid for....

A tunable orifice. (I can hear the :shake: jokes now….LOL) BUT you will still need to check the return flow.

As long as no damage is done, that was my main concern.

I don't know the internal routing of the fuel in the FASS, but I'm assuming the fuel still has to go thru both filters, which would be my 2nd concern.

So I would lose the air removal w/ this setup?

I won't comment on the tunable orifice...oke:

 

[zstroken]

As far as pump damage.....no.....BUT as far as a big waste of money...yes. You paid for the function of the FASS. Air removal and superior fuel filtering. When you cut off the return flow back to the tank...you loose all of that and you have an $800.00 HPFP at that point. The % of WOT to not is VERY lop sided...you prob spend about 2% if that on full throttle.....so 98% of the time the FASS would not be doing its thing that you paid for....



Exactly....you would use the FASS regulator to set your low pressure and then open up the external regulator to just start restricting the flow.

As for the Boost reference...this might need to be played with some. The way you could tune this is with an air regulator set to the PSI that would stick you at 50 PSI of fuel pressure under full boost. This could be very easily set with an air hose off a compressor with our pump running. You could mount this under the hood. I know if some regulators that give you, for example 1:1, 1:2, 1:5, 1:10 boost ratios. I think they tune with orifices...but don’t quote me on that.



Well the one way valve keeps a check on the system...it will not let it bleed back and loose prime. The return circuit is usually on the high side of the pump, so prime should no be lost. AND yes, you could use an orifice.....that is basically what a flow control valve is more or less. A tunable orifice. (I can hear the :shake: jokes now….LOL) BUT you will still need to check the return flow.

No jokes Dan, I just was afraid that someone could shut the flow control off, or it be plumbed in correctly. Think you could draw up a nice picture of the setup?

 

[Diesel-Dan]

As long as no damage is done, that was my main concern.

I don't know the internal routing of the fuel in the FASS, but I'm assuming the fuel still has to go thru both filters, which would be my 2nd concern.

So I would lose the air removal w/ this setup?

I won't comment on the tunable orifice...oke:

Yes you would...this drawing is very basic....but should explane the pump operation:

The return fuel is returned at the top of the filter and the engine draw is pulled from the bottom of the filter. You cut off return flow...you are only pull fuel from the bottom of the filter. You can do what you want....but if you have our systems....you might as will make use of it.....my 2 cents at least.

No jokes Dan, I just was afraid that someone could shut the flow control off, or it be plumbed in correctly. Think you could draw up a nice picture of the setup?

Ill see what i can do.......

 

[White Knight]

How small of a restriction do you think would be needed in the return line from the P-pump?
I have an old stock overflow valve that I'm planning to use as a banjo bolt for the outlet of the pump, I was thinking that I could remove the shims in it and let the weak spring and ball serve as a check valve to avoid any drain-down. The inlet orifice is about .105" do you think that would be small enough?



And does anyone know what size fitting is on the FASS return? I think its around a -6AN

 

[White Knight]

And to zstroken and GOT-Torque, what size is the 13105 regulator's reference port? 1/8"NPT?

 

[GOT-Torque]

Thanks Dan for the picture, it clarifies things. Your placement of the adj. regulator does seem to be a better setup, however I probably won't change anything until next year. I just got the engine installed last night...

White Knight, the inlet and outlet ports on the regulator have -6AN fittings on them. However, leaving the regulator I have to reduce it to -4AN to splice into the stock fuel return line (hard line w/ 1/4" inside diameter).